The flowering of plants causes a phase transition, which converts the growth of plants from vegetative growth to reproductive growth Most of plants have a mechanism by which the plant's flowering can be controlled such that the flowering occurs at a suitable time. This control mechanism of flowering time is influenced by genetic factors within plants, and external environmental factors (Lang A., Encyclopedia of Plant Physiology, Springer-Verlag, 1371–1536, 1965; Napp-Zinn K., In Manipulation of Flowering, London, Buttrworth, 123–132, 1987; and Poethig R. S., Science, 250: 923–930, 1990).
Recently, various studies on a control mechanism of plant's flowering time are being actively conducted on the dicot plant Arabidopsis thaliana through various genetic and molecular biological approaches. As a result, about 80 genetic loci involved in controlling the flowering time in Arabidopsis thaliana have been found, and four pathways controlling the flowering time have been found (Simpson et al., Annu. Rev. Cell Dev. Biol. 15:519–550, 1999; and Araki T., Curr. Opin. Plant Biol. 4:6368, 2001). The first pathway is a photoperiod-dependent pathway or a long day pathway, and genes known to be involved in this pathway include genes encoding a photoreceptor, such as phytochrome or cryptochrome, GI (GIGENTEA), CO (CONSTANS), FT (Flowering locus T), FWA (Flowering Wageningen), SOC1 (Suppressor of CO overexpression 1; AGL20) (Yaron Y. et al., The Plant Cell, 10:1973–1989, 1998). The second pathway is a vernalization pathway where the plant's flowering is promoted when plants are exposed to low temperature for a long time. As genes known to be involved in this pathway, genes, such as VRN1 (Reduced Vernalization Response 1), VRN2 (Reduced Vernalization Response 2), FRI (Frigida), and FLC (Flowering locus C), were cloned. The third pathway is an autonomous pathway where the plant's flowering is controlled while influencing both long-day conditions and short-day conditions. Genes involved in this pathway include FCA (Flowering locus CA), FVE, LD (Lurninidepedens) (Yaron Y. et al., The Plant Cell, 10:1973–1989, 1998). The fourth pathway is a gibberellic pathway where GA (gibberellic acid), a kind of plant hormones, plays an essential role and the pathway mainly having an effect on short-day conditions. It is reported that genes, such as GA1, GAI (GA Insensitive) and RGA (Repressor of gal-3) are involved in this pathway, and mainly, genes involved in the biosynthesis of GA hormones, or genes involved in the signal transfer of GA hormones, participate in this pathway (Araki T., Curr. Opin. Plant Biol., 4: 6368, 2001).
Attempts to artificially control the flowering time of plants using the genes involved in controlling the flowering time in plants, which were found as described above, are being conducted. Artificially controlling the flowering time of plants has a very important meaning in scientific viewpoints or industrial terms, such as agricultural or horticultural fields. The scientific study of a flowering control mechanism is very useful in establishing the initial embryogenesis and also organ development in higher plants. Furthermore, promoting the flowering time of horticultural plants in industrial terms allows flowers and seeds to be produced within a short time. Also, the flowering time of crops can be delayed to continuously induce the vegetative growth of the crops so that the production of useful portions from the crops can be increased.
U.S. Pat. No. 6,225,530 discloses an FT (flowering locus T) gene controlling the flowering time of plants, which is isolated from Arabidopsis thaliana, and also discloses a polypeptide encoded by the FT gene, and a method for controlling the flowering time of plants using the FT gene. Furthermore, U.S. Pat. No. 6,444,877 discloses a LSAG gene controlling the flowering time of plants, which is isolated from Liquidambar styraciflua (Sweetgum), and also a method for controlling the flowering time using the LSAG gene. Korean patent No. 319395 discloses a GIGANTEA gene controlling the biological clock and flowering time of Arabidopsis thaliana. 
However, since it is believed that the control of a plant's flowering time occurs through a significantly complex process and various genes which were not completely found are involved in this process, studies on new genes involved in the control of a plant's flowering time, and functions thereof, are required.